The problem is with the new maps proxi grenades would just make it really easy. First turn, get your guys to cover, lob em at the side of the map you want cover from. Then sweep the other side. Repeat for every map because it would be such an easy tactic. Same thing with the motion scanners, the maps don't really look like they're designed for you to use them over sight, especially with the snipers ability to throw those battle scanners.
The enemies all seem like they're going to attack you once you've gotten the ball rolling, so at most it would be a "enemies are here, here, here and here, roughly, therefore I will use all this cover to protect myself and never lose a unit". With the decreased squad size, I think they had make it a bit riskier when searching for enemies.
The delayed blast thing pissed me off though. At the very least, if you want an instant detonation, make it so you use both actions throwing a grenade instead of one. That way you could "cook it" before throwing. That way you would have to think about where to place your guy before you threw the damn nade. Aside from that, anyone with half a brain would realise grenades blow up a turn after they're thrown after using one for the first time, did they really take out delayed blasts just to spare them that? Pah
From a strictly game design point of view, I can see why they went the direction they did. I can see why its a tad annoying for classic players though.